Principal Investigator/Program Director (Last, First, Middle): Mayer, Kenneth H. Social/sexual networks of high risk married MSM in Mumbai ABSTRACT This proposal is in response to the RFP "U.S.-India Bilateral Collaborative Research Partnerships (CRP) on the Prevention of HIV/AIDS (R21)." This study proposes to evaluate the social and sexual network characteristics of high risk men who have sex with men (MSM) who are married to women in Mumbai, India. Fenway Community Health, the largest community-based US institution focusing on sexual minority health, proposes a partnership with the Humsafar Trust, Mumbai, and the National AIDS Research Institute (NARI), Pune. India has the greatest number of people living with HIV (NACO, 2006a), with more than 16 million people, Mumbai has the one of the largest concentrated HIV epidemics worldwide. Prior work from our group has documented that MSM seeking sexually transmitted infection (STI) screening services at Humsafar Trust (the principal non-governmental organization working with MSM in Mumbai) had an HIV prevalence of 21%. Many were married to women (25%), and married men were more likely to be HIV-infected and engage in unprotected anal and vaginal intercourse with both male and female partners compared to unmarried MSM (Kumta et al., 2006a;2006b). These data suggest that this subset of urban Indian MSM might be a particularly important "bridge" population that could amplify the HIV epidemic in India, and thus this study has huge public health relevance. Most research to date investigating behavioral risks and HIV/STI prevalence and incidence concerning Indian MSM has been based on convenience sampling, and has not been able to define the social interactions of diverse MSM subgroups sufficiently to inform culturally-relevant HIV prevention and intervention strategies based on well-characterized behavioral epidemiological data. Over the past 5 years, a collaboration of academically-affiliated New England investigators based at Fenway Community Health have worked with Humsafar Trust to develop the infrastructure to conduct community-based research in sexual minority populations, including the establishment of their freestanding IRB, and provision of technical training related to the optimal conduct of community-based research. The current proposal represents the first NIH application by this consortium to use a respondent-driven sampling recruitment method to recruit a maximally diverse cohort of married, compared to non-married MSM in India. The overall goals are to better understand HIV/STI transmission dynamics and how social and sexual network characteristics contribute to increased risk, and to probe for interest in participating in future HIV/STI prevention interventions. This information will be used to design future biobehavioral prevention interventions at Humsafar Trust/NARI, including recruiting high risk cohorts, measuring HIV and other STI incidence and prevalence, and documenting successful strategies for identifying, tracking, and retaining high risk participants.